This is why I wont ever use Seafoam. If it comes down to it, I'll rebuild the engine myself.
These 4.0's generally do not build up much carbon because the air/fuel mix is monitored and managed accordingly. However, every engine has some carbon build up. And with the miles the engine had on it, it could very well have been worn ever so slightly and the carbon had kept everything comfy. Now that the carbon is gone, the oil gets to go wherever it pleases, and that includes the combustion chamber.
Then again they could be unrelated, and just be coincidence. I would refill the oil to make sure that you did fill it completely then troubleshoot from there.
